1. Field of the Invention
The present invention relates to an image display unit to which a film image signal generated based on a cinema film is inputted as a video signal.
2. Description of the Related Art
In general, in motion picture photography, still images are recorded in a cinema film at a frame rate of 24 frames per second. In a movie theater, moving picture is displayed by sequentially projecting the cinema film at a rate of 24 frames per second by a cinema projector. That is, movie display at a frame rate of 24 frames/sec (24 Hz) is performed.
Meanwhile, a frame rate of an ordinary TV (television) signal is 50 frames/sec (50 Hz) or 60 frames/sec (60 Hz). Thus, in the past, processing referred to as television cinema conversion (telecine conversion) in which, for example, a film image signal with 24 frames/sec is converted to a signal format of the ordinary TV signal has been performed. Examples of telecine conversion include 2-2 pulldown and 2-3 pulldown. For example, in the case where a film image signal with 24 frames/sec is converted to an image signal with 60 frames/sec, 2-3 pulldown is used. For example, where the first frame image in film images is A and the next second frame image in the film images is B, in 2-3 pulldown, image sequence “AB” in the film images is converted to image sequence “AABBB” in 60 frame images. That is, 2 frame images are generated from the first frame image of the film images, and 3 frame images are generated from the next second frame image, and thereby 5 frame images are generated from 2 frame images. By performing the same conversion for 24 frames, 60 frame images are generated. Such 60 frame images are contained in 1 second display time period, and thereby a signal format with 60 frames/sec is obtained. Similarly, in 2-2 pulldown, processing is performed so that image sequence “AB” in film images is converted to image sequence “AABB.” That is, in 2-2 pulldown, 2 frame images are sequentially generated from each frame image of the film images.
The signal that is provided with pulldown processing has a feature in the image array. Thus, in an equipment of reproducing a picture, it is possible to detect that an input video signal is a film image signal generated based on a cinema film by detecting the image array. Such a technique is referred to as film detection, which has been known in the past as described in Japanese Unexamined Patent Application Publication No. 2005-130286.
A video signal inputted to a TV receiver or the like is outputted by being converted to a TV signal with 50 Hz or 60 Hz in a stage of being transmitted from a broadcast station or a stage of being transmitted from a VCR, even though the original picture thereof is a cinema film image.
Meanwhile, in recent years, audiovisual environment of a motion picture content in an ordinary household easily has similarity to cinema film showing in a movie theater. For example, with regard to size and definition degree of screen, a large and horizontally long TV display with high definition has been commonly used in ordinary households. Further, as a display method of a TV display, liquid crystal display method has been commonly used instead of CRT (cathode-ray tube) method. Thereby, instead of the interlace scan method that has been used in the existing CTRs, display with the use of progressive method has been commonly used. Therefore, in recent years, in a TV receiver or the like, even if an input video signal has not been converted to a TV signal with 50 Hz or 60 Hz, a film image signal with 24 frames/sec is allowed to be displayed at the original frame rate. Such a display method is referred to as 24p reproduction or the like. 24p reproduction is performed, for example, in the case where a 1080p24 signal is inputted with the use of HDMI (High Definition Multimedia Interface) input.
As described above, in recent years, in a liquid crystal TV or the like, display on a big screen with high definition at the same frame rate as that of a cinema film has been enabled, and thus the household audiovisual environment easily has similarity to that of cinema film showing in a movie theater. Meanwhile, a panel device of a liquid crystal TV or the like is a so-called hold type display. Thus, in a picture with 24 frames/sec such as a motion picture content, judder is easily visible. Visibility degree of judder is increased in the bigger screen, leading to sense of discomfort. In the hold type display, once an image is displayed, such a displayed image is continuously displayed until the next image is displayed. That is, in the case where picture does not change between frames, data is not refreshed, and the same picture is continuously displayed. Thus, if a subject moves at a time of switching between frames, the subject is seen as a double image due to human visual feature. Such a phenomenon is called judder.